What if your airplane carried so much fuel it couldn't carry any passengers?
Once battery technology improves they can offer longer ranges without sacrificing too much cargo capacity. For now they think they can be cost-competitive for routes that can deal with a 500 mile range (shorter routes where you can charge when you offload at your destination) and local delivery (start and end your daily route at the local warehouse where you can plug in). If they try to target longer routes they'll have to increase costs of each truck dramatically (for the added battery capacity) and lower hauling capacity, which also increases costs to the trucking company because they'll need more trucks and drivers (until they can get rid of human drivers) to move the same amount of cargo as they could with diesel semi-trucks. If quick chargers were installed at most interstate truck stops, then a cross country route becomes possible even with a 500 mile range.
Think about a WalMart distribution center. Take for example, the one in Lewision Maine. I think there is only one WalMart in Maine that isn't within a 500 mile round trip from the this distribution center. Those are perfect routes for the Tesla. They don't have to take over the entire trucking industry at once.